DESCRIPTION: This is a proposal to investigate chromatin assembly factors in yeast, using complementary genetic and biochemical approaches. The PI will focus on a yeast protein complex termed Chromatin Assembly Factor-I (CAF-I) that assembles histones H3 and H4 preferentially onto replicated DNA in vitro. Cells containing null alleles of the genes encoding CAF-I subunits are viable but display altered sensitivity to hydroxyurea and benomyl, drugs that disrupt the cell cycle. The PI will test these mutants for defects in chromatin structure, gene expression, and cell cycle checkpoint control. To determine if redundant assembly activities account for the survival of cells lacking CAF-I, the PI will screen for mutations that generate a requirement for intact CAF-I and for high copy suppressors of the drug sensitivity phenotypes of CAF-I mutants. Epitope-tagged yeast CAF-I subunits will be used to isolate proteins bound to CAF-I in vivo. Proteins identified by these methods will be tested in biochemical assays.